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    <title>Document</title>
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    <script>
        function reverse(arr) {
            if (arr instanceof Array) {
                var newArr = [];
                for (var i=arr.length-1; i>=0; i--) {
                    newArr[newArr.length] = arr[i]
                }
                return newArr
            } else {
                return 'error 这个参数要求必须是数组格式[1,2,3]'
            }
            
        }
        var arr1=[1,35,32,5,6,3] 
        var arr1=1 //error 这个参数要求必须是数组格式[1,2,3]
        console.log(reverse(arr1)); 
    </script>
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